1. Field of the Invention
The present invention relates to a dense composite material, a method for producing the same, and a component for semiconductor production equipment.
2. Description of the Related Art
A cooling board for dissipating heat is joined to an electrostatic chuck whose temperature becomes high in a semiconductor process. There may be a case where alumina is used as a material for the electrostatic chuck, aluminum is used as a material for the cooling board, and resin is used as a joining material. There is a large difference in coefficient of linear thermal expansion between alumina and aluminum. For example, the coefficient of linear thermal expansion of alumina is 7.9 ppm/K (RT-800° C.): Uchida Rokakuho Publishing Co., Ltd., “Seramikkusu no Butsuri (Physics of Ceramics)”), and the coefficient of linear thermal expansion of aluminum is 31.1 ppm/K (RT-800° C.: “New edition of Thermophysical Properties Handbook” edited by the Japan Society of Thermophysical Properties). In such an electrostatic chuck, since soft resin is used as the joining material, it is possible to relax stress caused by the difference in coefficient of linear thermal expansion. However, since resin is an organic material, it has characteristics that it has a low heat dissipation property, is likely to decompose at high temperatures, and is likely to degrade with time. Therefore, such an electrostatic chuck is hard to use in a high-temperature process for a long period of time. Accordingly, it has been confirmed that a metal junction is effective as a joining material having a high heat dissipation property that replaces the resin. In the metal junction, for example, aluminum, solder, silver solder, or the like is used as a joining material. However, unlike resin, metal is not soft, and it is not possible to relax stress caused by the difference in coefficient of linear thermal expansion between the electrostatic chuck and the cooling board.
In the case where a metal junction is employed for joining an electrostatic chuck and a cooling board to each other, the cooling board needs to have characteristics that it has a small difference in coefficient of linear thermal expansion from the electrostatic chuck, a high thermal conductivity in order to maintain the heat dissipation property, high denseness in order to pass a cooling liquid or cooling gas therethrough, and high strength to endure processing, installation, and the like. An example of a material that satisfies such characteristics to a certain extent is a composite material disclosed in Patent Literature 1. This composite material is a TiC base Ti—Si—C-based composite material having a phase including 1.0% to 20.0% by volume of Ti3SiC2, 0.5% to 8.0% by volume of SiC, and the balance being TiC. Since the difference in coefficient of linear thermal expansion between TiC and alumina is small, it is considered that the difference in coefficient of thermal expansion between the Ti—Si—C-based composite material containing the TiC base as a main phase of Patent Literature 1 and alumina is also small.